A New Dimension
by violinnerd 14
Summary: 4 years after defeating Callahan, Hiro rebuilds the portal and traveled through. When he arrives in San Fransokyo, he is not surprised, until a face from the past returns. Can Hiro and Baymax get back to their dimension with the help of the other universe's team, and the input of a certain older brother?
1. Chapter 1

**Hey it's Vy! So here's my first Big Hero 6 attempt, so we'll see what happens. Hope you guys like it! Disclaimer: I sadly don't own BH6**

"Ok Baymax, ready?" 18 year old Hiro Hamada asked his robot.

"I fail to see how this improves your health. Or improve anything at all," the large balloon-like invention stated.

"I fail to see how you fail to see how cool it is!" Hiro exclaimed. He put on his purple helmet and walked over to the control panel for the large ring in front of the pair. After defeating Callahan, Hiro and the team rebuilt the portal that almost killed Abigail and ended up being the original Baymax's final adventure. Since then Hiro had grown up. His old armor had changed. He kept the original helmet with the exception of making it a darker shade of purple and red (making small adjustments for comfort). He now had dark purple (almost black) and red coloring and a little more bad ass theme going on. That didn't change the fact that he was still really tiny though. He did have other clothes on under the armor too, so he could change to look normal depending on where they ended up. Hiro pressed the final button and the machine turned on, glowing.

"Ready Baymax?"

"Of course." Baymax leaned down and Hiro climbed onto his back. Then they took off, into the portal. Soon enough they ended up in a back alley way. Hiro quickly undid the straps of his armor, which folded up conveniently, and revealed a black tee shirt that had SFIT written in faded red letters, blue jeans, and the old blue hoodie he always wore. He got Baymax's armor off and stuffed it into a small backpack he managed to bring with. Looking around the corner, Hiro was slightly disappointed.

"Well, we're still in San Fransokyo that's for sure," he said. He had hoped for a more exciting destination on their first trip. He ran a hand through his messy black hair, now a few inches shorter than before.

"Well Baymax, might as well start walking home," he said.

"Hiro?" A voice asked from the dark. Hiro to froze, only one person had that voice.

"Hello, I am Baymax, your personal health care companion," Baymax told the newcomer. Hiro turned, and almost screamed. How was _he_ standing _there_?!

"Hiro?" The man asked again, and Hiro knew just who it was.

"Tadashi?"


	2. Chapter 2

**Hey it's Vy! And since Christmas was yesterday, I'm updating all my stories! Love ya guys! Happy holidays! Sorry for the short chapter. Review, follow, favorite. Disclaimer: I don't own :(**

"See you later Aunt Cass!" Tadashi called to his aunt as he walked out. Finals had just finished at SFIT, and he thought he should take a walk. The city was so lively, even at night, so it wasn't too much different. As he walked, he heard shouting come from a dark alleyway, and the sound of a small crowd cheering. Bot fighters. Tadashi quickened his pace. It had been four years since his little brother Hiro died, but it still hurt. Not noticing where he was going, he continued on. As he passed a slightly lighter alley (in a safer part of town luckily), he heard a strange noise, like electricity. Confused, he went towards the sound. Suddenly a blue light flashed from around the corner, throwing him off guard. He rubbed his eyes and turned the corner.

"Well we're still in San Fransokyo," a boy's voice said. Tadashi froze. Was that? No, there's no way it's him.

"Well Baymax, might as well start walking home," the voice said. There was no doubt in Tadashi's mind now. Only one other person could be out with Baymax, no matter how impossible it seems. But there's no mistaking the voice of Hiro Hamada.

"Hiro?" Tadashi asked, coming around the corner completely. The other boy stiffened. Tadashi looked at him in shock. If he had passed this teen on the streets he never would have thought it was his brother. He had grown, now about the same height as Tadashi, and he had pierced his ears. His hair was still a long mess of black, luckily.

"Hello, I am Baymax, your personal health care companion," his robot said, waving to him. Tadashi ignored it.

"Hiro?" He asked again. Hiro turned. Shock entered his eyes as he saw his older brother.

"Tadashi?" He asked.


	3. Chapter 3

**Hey it's Vy! **

**Guess who's been Crap at uploading stories? *raises hand* Sorry! I have had the worst writers black for all my fanfiction and then I just kinda lost motivation but here's more of A New Dimension! Enjoy! Disclaimer: I don't own**

I think my eyes are playing tricks. There is no way Tadashi is standing there.

"Hiro? How are you here?" He asked. I guess the feeling goes both ways.

"I came through the teleport. What about you?" I ask, trying to pretend this was normal. Tadashi didn't look any different from when he died, but I knew I'd changed. I can't believe he recognized me.

"I was on a walk and heard a weird sound so I followed it and found you," he explained. "But how do you have Baymax? I thought I disabled him. Not to mention you shouldn't even be able to do anything let alone walk around town!"

"What do you mean? You're the one that shouldn't be able to do anything! You're-" I stopped in this place my brother was alive. How? What was the date? Am I even in the San Fransokyo I know?!

"I'm what?" He asked.

"Nothing," I said, waving my hand.

"How about we go talk. I have a feeling we have two different stories," Tadashi suggested. I nod. He led the way to the nerd school, which I guess made sense. No one would bother us there. We didn't talk on the way there, leaving that for when we told our stories. The only sound was Baymax walking behind us. Once we arrived we went straight to his lab, and I hit the spacebar on his computer.

The screen glowed, showing the date. September 5, 2015,?! How?! When I left it was 2019! According to this computer my college entrance presentation was a month ago.

"Tadashi I think your computer has the wrong date," I said. He came and looked.

"Nope. That's the right one. Why?" I consider my options. I can't tell him everything, if that dumb portal sent me back in time I'd mess everything up.

"I came from a different year," I said slowly.

"How? Time travel is impossible!"

"I guess not. Back home, there was this broken portal created for teleportation. I fixed it and decided to try it out. I guess it brought me to a new dimension," I said, looking around thoughtfully.

"Ok, then tell me why this date's important to you. There has to be some reason you're here," Tadashi said, sitting down. I sat down and explained.

"For me, this is a month and about a year after someone died. I accidentally activated Baymax at home, and he wanted to go for a walk around town with my microbot and found a factory making thousands of them. I don't really know what else to say."

"Huh. It's been about a year for me too, I lost someone to a fire. Today I threw out my plans for Baymax, burning them. I had already disable him," Tadashi looked sad as he said this. "And since you said Baymax was at home, I'm guessing I'm the person you lost?" I look up in surprise. I forgot how good Tadashi is at reading people.

"Yeah," I said. "It was the night I presented my microbots. I had my letter, I was going to nerd school with you and your friends, no more bot fights-"

"I have to stop you there, no more bot fighting?! Something must have possessed you cause I never thought I'd hear those words," Tadashi teased.

"Yeah yeah yeah," I laughed. "Anyway, everything seemed perfect to me. But the building went up in flames, with Callaghan still in there. You went in to save him and," I couldn't continue.

"It exploded," Tadashi finished.

"How did you know?" I ask, a terrible feeling filling me.

"On that same night, the same thing happened but you ran in instead," Tadashi said sadly. "Before you entered the building exploded, injuring you. I went straight to Baymax, who operated for about an hour. But you died after. I was so mad, I kept saying it was my fault. If Baymax was built better you wouldn't die! I disabled him in my anger, saying I was done with that project."

"I know the feeling," I told him.

"I thought if I tried harder to stop you then you wouldn't die. But hey, you're here now. Right in front of me!"

I grin. I can't stay here forever, we both knew that. And he can't go back with me. But at least I can talk to him again. He laughed.

"That's true. So did you still go to school knucklehead? You better not tell me you dropped out!" I laughed too.

"I went to your nerd school Nerd," I told him.

"Now that you go here you're a nerd too you know," he pointed out.

"But I'm the coolest nerd," I said. He laughed.

"Well you're certainly going for a more 'tough' look aren't you?" He teased, gesturing to my new outfit and longer hair. I laughed.

"I was going for a more 'bad ass' theme with this." I pulled my hair back, revealing multiple ear piercings along both ears. "How'd I do?" Tadashi's eyes widened.

"Well Knucklehead, I never thought you'd go as far as piercing your ears," he admitted.

"Hey! I'm tough!" I joked, pretending to punch Tadashi, who dodged it.

"So you have piercings. Any tattoos I should know about? More bot fights? Secret girlfriends?" He joked, and I gasp dramatically.

"You think I'd cheat on my girlfriend! That is low Tadashi," I joke.

"So there is a girl," he said triumphantly. I roll my eyes.

"No there isn't Idiot. I am single and would rather not mingle." He laughed. "Anyway, what about you and Honey Lemon? I'm pretty sure you two were secretly dating," I say, smirking.

"That, is a story for another time," he said, and I laugh.

"Yup. Totally dating."

"Shut up!" He says, laughing with me.

Down the hall I hear a door slam, and laughter ring through the hall way.

"I thought no one else was here?" I ask, and he shrugs.

"I thought so too." We sit in silence for a few moments, and I open my mouth to ask him something when the door flies open.

"Tadashi! What are you doing here so late?" Honey Lemon's voice rang through the room. I turn to see the gang, Honey, Gogo, Wasabi, and Fred, filing into the room. Wasabi, who was leading the group, froze, the others crashing into him.

"Hiro?" He asks, and everyone looks around him to me, and I see four jaws drop at the same time.


	4. Chapter 4

**Hello and welcome to some long overdue Big Hero 6! I'm sorry this took so long, but hopefully the rest of the story won't have such a bad wait. Anyways, here's the new chapter! Enjoy!  
**

* * *

"Um Tadashi, are you making a robot that looks like your dead brother or something?" Wasabi asked, clearly freaked out. Tadashi looked to me, hiding his laughter and responded seriously, "Yes." Wasabi gasped and Honey and Gogo just shook their heads.

"Seriously? Dude that is so cool!" Fred exclaimed, jumping over and looking at me. I froze, waiting for the perfect moment.

"Why'd you pierce his ears? And his hair is different… I like the SFIT shirt though! When did they start selling those?" he asked, reaching out to touch an earing. I slap his hand away.

"Dude, respect the earring," I joked. He jumped back.

"Woah! That is not a robot! Not a robot!" he practically yelled, running to hide behind Gogo, who stepped aside so he was visible. I roll my eyes and Tadashi burst out laughing.

"No, hardly a robot," he said in between gasps of laughter.

"Tadashi calm down," I say, laughing just as hard myself.

"Um, I hate to interrupt this brotherly moment, but do you care to explain why your brother is here?" Gogo demanded. Tadashi shrugged, his laughter dying down.

"I'm not too sure myself.," he admitted. All eyes turn to me. I consider my options for a moment.

"It's a long story," I say slowly. Gogo crosses her arms.

"We've got all night." Tadashi and I glance at each other and I shrug, turning back to face everyone.

"Ok, long story short I come from an alternative dimension. I came through a portal with Baymax from the year 2019, so I guess I'm you ages now," I said, smirking. Gogo rolls her eyes.

"Of course you would think that's the most important information," she said sarcastically. I grin.

"Believe me, it is. You can't boss me around anymore," I joke, imitating her and crossing my arms, leaning back in my chair. Tadashi rolls his eyes.

"What are you guys doing here so late?" he asked. "I thought you finished your final projects." They shrugged.

"I had to finish up a couple notes for my reactions, Gogo tagged along to try and increase the speed on her bike, Wasabi was cleaning up still, and Fred was just here," Honey Lemon explained, pointing to each in turn. Tadashi nodded, considering this.

"Maybe, or maybe you were just here to see me," I joke, smirking. Gogo snorted, but smiled anyway.

"And why would we do that? I don't know what it's like where you're from, but here we don't know you that well," she pointed out. Wasabi looked surprised.

"Gogo! Why would you say that?!" he hissed. She shrugged.

"It's true. We only knew him for a few weeks," she said. This was a fair point. Wasabi seemed to have realized this too, for he didn't question it any further. He distracted himself from the small awkward moment by looking around the room, almost as if he'd never seen it before, and Fred finally returned to the conversation. Granted he had dug up that old mascot fish head he used to wear all the time, but he returned nonetheless.

"Well this has all been great fun-" Tadashi started.

"We are really busy so see you tomorrow!" I finished, interrupting Tadashi and pushing the gang out of the door, ignoring their protests and Fred's comments on 'when did I get so strong?' Wasabi, who was in the front of the group, stopped at the door, blocking the rest from getting pushed through.

"Nope, I demand an explanation! There's no way you can just return from the dead, suddenly five years older, and not expect us to want answers!" he said, turning and crossing his arms. I shook my head, ignoring the hair that fell into my face.

"Sorry we're closed for the night, come back in the morning," I say, giving up on pushing them away and sitting back down on an office chair.

"Wait, Hiro, maybe we should tell them more? I mean, you haven't told me much either, but maybe we can figure out a why to get you back?" Tadashi proposed. I shook my head again.

"Nope, sorry. Story time's over," I insist, standing up and trying to push them out the door yet again.

Fortunately for me, Honey caught on quickly that I wasn't going to give up any time soon, and helped ushering the others out of the lab. I gave her a grateful smile and closed the door behind them, leaning against it and sliding down to the floor. Tadashi was still where he started,watching the encounter with an amused smile on his face.

"Great job there little bro. I almost thought you wouldn't be able to handle them," he said, laughing. As childish as it was, I stuck my tongue out at him, before joining him in laughter.

"And you were absolutely no help," I pointed out, and he shrugged.

"What would you do if I did everything for you? You'd be bored out of your mind." It was my turn to shrug.

"It'd still be nice," I insist. Tadashi laughs, standing up and walking to the charging station, where Baymax had been standing quietly.

"Whatever you say Hiro," he teased, turning off the station and waking Baymax up. The healing robot looked up, powering up must have lost more energy than I expected when we went through the portal.

"Hello, I am Baymax, your personal healthcare companion," he greeted, waving to his creator. Tadashi smiled, looking at the robot with an expression of undeniable pride.

"Hey Baymax, welcome back," I said, standing and joining my brother.

"Hello Hiro," the robot said, turning towards me. Tadashi shook his head, the smile still on his face.

"Well, as much fun as this has been, we better get you two home," he said, walking away to get his jacket from the corner.

"Wait, what do you mean 'home?' The portal closed, remember?" I questioned. Tadashi rolled his eyes.

"You forget that we still live in San Fransokyo. I'm sure Aunt Cass will let you stay until we can get you back to your dimension," he explained.

"Are you sure? I feel like reintroducing her dead nephew might be a bad idea," I said tentatively. Tadashi brushed this worry away.

"She's your aunt, what's she gonna do?" I consider this question.

"I don't have an example but I know it could be bad," I say, trying to prove a point. Tadashi wasn't taking it.

"Too bad. You're coming home for now," he said, holding the lab door open for me. I stand stubbornly, arms crossed.

"Can't I stay here?" I ask hopefully. But Baymax was already halfway out the door.

"Come on Hiro, even Baymax wants to go home." I consider the options, and groan, following my robot out the door.

"Thank you," Tadashi said, locking up behind us.

"Yeah yeah," I say, walking on. I hear a small laugh come from Tadashi, and a quiet comment on 'how little I've changed.' We walk home in silence, much like the walk to nerd school, but more comfortable this time.

When we finally reach the Lucky Cat Cafe, it's Tadashi that suggests he go in first. I don't complain, happy to wait while he talks to Aunt Cass. He enters the house and I sit at one of the tables, looking around the cafe in curiousity. It's not much different from the one at home. A sad air hangs around it, and I wonder if it had anything to do with the death day anniversary. A small noise snaps me out of these thoughts, and I look down to see a fat cat rubbing against my leg. I smile, leaning down and picking him up.

"Hey Mochi," I say happily, scratching the cat behind the ears. He purrs, curling up in my lap, completely oblivious to the large white balloon called Baymax that was standing by the door.

"Hey Hiro?" I turn to see Tadashi in the door, motioning for me to come inside.

"Someone is expecting you to say hi," he said with a smile. I swallow nervously and put the cat down, ignoring his meow of discomfort, and enter the hallway to the house. Baymax follows of course, surprisingly silent, and Mochi runs ahead. Tadashi falls behind as he goes to lock up the cafe for the night as I start climbing the stairs to our living room.

I reach the top of the stars and looking around, noticing how different it was from my home. Nothing huge of course. A color change here, a different picture there, stuff like that. I was apparently more distracted by these than I thought, because I didn't realize I wasn't alone for quite some time.

"Hiro?"

I freeze, turning for yet another reunion, yet I was less prepared for this one than I was for Tadashi's .

"Hey Aunt Cass."


End file.
